It’s weird, every time I’ve talked to Amazon support they’ve always done well. Did they refuse to refund you or let you return it?
Amazon regularly commingling legitimate and counterfeit goods, means that customers are left with the job of trying to verify that the goods they ordered are legitimate. For every customer that complaints & refunds, there might be three or more who don't.
Some of these counterfeit products have legitimate safety concerns, for example lead paint usage, battery fire risks, PPE that misstates its effectiveness, or USB chargers with poor AC DC electrical isolation.
This is a huge trust problem, and "the customer needs to detect counterfeits and refund," isn't actually a solution to THAT problem.
Amazon could then persue the manufacturer for sending bad goods.
Sue them? Even assuming that kind of time, money, and energy expenditure is within their resources, Amazon's legal department is likely to be able to stonewall until they run out of money.
Then multiply that by however many thousands or tens of thousands of customers Amazon has done this to. No more than a fraction will ever complain, no more than a fraction of those will ever sue.
Amazon has been allowed to get too big, and the usual methods of dealing with fraud at this level simply don't work reliably.